DE102011110906A1 - A method and apparatus for controlling a high voltage battery connection for a hybrid powertrain system - Google Patents

Abstract

A hybrid powertrain system includes a high voltage electrical circuit including a high voltage battery and a DC coupling coupled to first and second rectifiers / inverters electrically connected to first and second torque machines. A method of operating the hybrid powertrain system includes receiving a motor torque command for the second torque machine, determining a preferred DC link voltage to achieve the motor torque commanded from the second torque machine, and an electrical power flow between the high voltage battery and the DC link is selectively interrupted to achieve the preferred DC coupling voltage.

Description

TECHNICAL AREA

This disclosure relates to high voltage electrical systems for vehicles incorporating powertrain systems.

BACKGROUND

The statements in this section provide only background information related to the present disclosure and may not form the prior art.

Known vehicle systems use hybrid powertrain architectures to provide at least part of what is needed. To generate driving torque that comes from a non-hydrocarbon powered engine that includes an electric machine that transforms electrical power into mechanical torque. Powertrain architectures may be configured to transmit drive torque through a transmission device to a dispense element. Such powertrain architectures may include serial-hybrid configurations, parallel-hybrid configurations, and composite-branched hybrid configurations. Electric machines, which may be operated as both motors and generators, may be controlled to generate torque inputs to the transmission independently of torque input from an internal combustion engine. The electric machines can respond to kinetic energy of the vehicle transmitted by the vehicle driveline and transform it into electrical energy that can be stored in an electrical energy storage device. A control system monitors various inputs from the vehicle and the operator and provides powertrain operational control including controlling the transmission operating range status and gearshifts, controlling the torque-generative devices, and regulating the electrical power exchange between the electrical energy storage device and the electrical machines Manage torque and speed outputs of the transmission.

Known electrical circuits for providing electrical power to electrical machines include a high voltage electrical DC energy storage device that provides DC electrical power by DC coupling to a rectifier / inverter by DC coupling the electrical DC power into electrical AC power. Power transformed to power the electric machine. The electric machine is preferably a multi-phase synchronous AC machine including a stator and a rotor magnetically coupled to the stator.

The performance of an electric machine, specifically the generation of torque for either the drive or the reaction associated with the regenerative braking, is limited by the magnitude of the DC voltage at the DC coupling to the rectifier / inverter.

The power capacity of the serial link to and from the DC high voltage bus is limited by a magnitude of the voltage at the DC coupling to the rectifier / inverter which affects the output of mechanical power from the electric machine connected thereto. The magnitude of the voltage at the DC coupling to the rectifier / inverter may be limited by the magnitude of the DC voltage available from the DC high voltage electrical energy storage device and transmitted to and from the DC high voltage electrical energy storage device.

One known solution for increasing the magnitude of a voltage across the DC coupling to the rectifier / inverter involves the use of a high voltage DC electrical energy storage device that has a higher voltage level than the high voltage DC electrical energy storage device. Another known method for increasing the magnitude of a voltage across the DC coupling to the rectifier / inverter involves adding a DC / DC boost converter between the DC high voltage electrical energy storage device and the DC coupling to the rectifier / inverter. Another known method of increasing the magnitude of the voltage at the DC coupling to the rectifier / inverter involves adding an ultra-capacitor bank to the DC coupling to the rectifier / inverter. Each of these known solutions requires installation space in the vehicle, increases the weight and increases the complexity of the electrical system.

SUMMARY

A hybrid powertrain system includes a high voltage electrical circuit including a high voltage battery and a DC coupling coupled to first and second rectifiers / inverters electrically connected to first and second torque machines. One method of operating the hybrid powertrain system includes receiving a motor torque command for the second torque machine, a preferred DC link voltage to achieve the commanded one Motor torque is determined by the second Drehmomentmnaschine and the flow of electrical power between the high voltage battery and the DC coupling is selectively interrupted to achieve the preferred DC coupling voltage.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments will now be described by way of example with reference to the accompanying drawings, in which:

1 schematically illustrates a drawing of a vehicle including a hybrid powertrain system including an engine, a hybrid transmission, a torque machine, and a driveline in accordance with the present disclosure;

2 Schematically showing details of an electric circuit of a hybrid powertrain system including a high voltage battery connected to a high voltage bus connected to a rectifier / inverter module and first and second torque machines according to the present disclosure;

3 schematically shows a control scheme for controlling the operation of an electric circuit for a hybrid powertrain according to the present disclosure; and

4 FIG. 2 graphically depicts a simulated operation of a hybrid powertrain system, which is described with reference to FIG 3 described control scheme according to the present disclosure.

PRECISE DESCRIPTION

Referring now to the drawings, wherein the illustrated is intended only for the purpose of illustrating certain example embodiments and not for the purpose of limiting the same 1 a schematic way a vehicle 100 that is a hybrid powertrain system 20 contains that with a final drive 60 is coupled and through a tax system 10 is controlled. Throughout the description, like reference numerals designate like elements. The hybrid powertrain system 20 contains a mechanical power train that is an engine 40 and first and second electrically operated torque machines (MG A) 35A and (MG B) 35B Contains that with a hybrid transmission 50 are mechanically coupled, which is a Abgabeclement 62 has that with the final drive 60 is coupled. A high voltage electrical circuit includes a high voltage battery 25 using a high voltage bus 29 with a rectifier / inverter module 30 electrically connected. The rectifier / inverter module 30 contains first and second electrical rectifier / inverter 32A respectively. 32B ,

The engine 40 is preferably an internal combustion engine with multiple cylinders and direct fuel injection, which converts fuel through a combustion process into mechanical power. The engine 40 is equipped with a plurality of actuators and detection means for monitoring the operation and supplying fuel for forming a combustion charge to generate a torque responsive to an operator torque request. In one embodiment, the engine is 40 is configured to operate as a spark engine, wherein the combustion timing and associated engine torque are controlled by advancing or retarding the spark firing timing. Alternatively, the engine 40 configured to operate as a compression ignition engine, wherein the combustion timing and associated engine torque are controlled by advancing or retarding the timing of fuel injection events.

The first and second torque machines 35A and 35B preferably include multi-phase electric motors / generators configured to convert stored electrical energy into mechanical power and to convert mechanical power into electrical energy stored in the high voltage battery 25 can be stored.

The gear 50 preferably includes one or more differential gear sets and activatable clutch components for torque transfer across a range of speeds between the engine 40 , the first and second torque machines 35A and 358 and one with a vehicle driveline 60 coupled delivery element 62 to effect.

The final drive 60 can be a differential gear device 65 included with an axis 64 or mechanically coupled to a half-wave, which in one embodiment with a wheel 66 is mechanically coupled. The differential gear device 65 is also with the delivery element 62 the hybrid powertrain system 20 coupled. The final drive 60 transfers drive power between the hybrid transmission 50 and a road surface.

In the engine 40 resulting mechanical power can via an input element 33 to the first torque machine 35A and about the hybrid transmission 50 to the delivery element 62 be transmitted. In the first torque machine 35A resulting mechanical power can over the input element 33 to the engine 40 and about the hybrid transmission 50 to the delivery element 62 be transmitted. In the second torque machine 35B Mechanical power can be generated via the hybrid transmission 50 to the delivery element 62 be transmitted. Mechanical power can be between the hybrid transmission 50 and the final drive 60 via the delivery element 62 be transmitted. Operating parameters associated with such mechanical power transmission include an output torque T _o and a output speed N _o .

The high voltage battery 25 stores potential electrical energy and is over a high voltage bus 29 who has a positive side 29A and a negative side 29B contains, with the rectifier / inverter module 30 electrically connected to the first and second torque machines 35A and 35B connected to transmit electrical power in between. It should be noted that the high voltage battery 25 an electrical energy storage device may include a plurality of electrical cells, ultracapacitors and other devices configured to store electrical energy in the vehicle. An exemplary high-voltage battery 25 contains a variety of lithium-ion cells. With the high voltage battery 25 Connected parameter states include a state of charge, temperature, available voltage, and available battery power, all from the control system 10 be monitored. The available battery power describes battery power limits that are permissible. Range between a minimum and a maximum allowable battery power, which are described as a maximum charging power (Pbat-Max charge) and a maximum discharge power (Pbat-Max discharge). It should be noted that the battery power is measured using a parameter that can be monitored regularly, eg. As the state of charge (SOC) or another suitable parameter. The allowable battery power limits are preferably set at threshold levels to both over-charge and over-discharge the high voltage battery 25 which can lead to a reduction in their lifetime.

The rectifier / inverter module 30 contains first and second rectifier / inverter (IMA) 32A and (IMB) 32B that with the first and second torque machine 35A respectively. 35B are electrically connected. The first and second torque machines 35A and 35B interact with the respective first and second rectifier / inverter 32A and 32B to convert stored electrical energy into mechanical power and to convert mechanical power into electrical energy stored in the high voltage battery 25 can be stored. It should be noted that the first and second electrical rectifier / inverter 32A and 32B can be operated to transform electrical high voltage DC power into high voltage electric AC power and also can be operated to transform high voltage electric AC power into high voltage electric DC power. Electrical power in the first torque machine 35A can be created via the rectifier / inverter module 30 and the high-voltage bus 29 to the high voltage battery 25 and via the rectifier / inverter module 30 to the second torque machine 35B be transmitted electrically. Electrical power in the second torque machine 35B can be created via the rectifier / inverter module 30 and the high-voltage bus 29 to the high voltage battery 25 and via the rectifier / inverter module 30 to the first torque machine 35A be transmitted electrically. Additional details with respect to an exemplary rectifier / inverter module 30 be related to 2 and the associated description provided.

The tax system 10 contains a control module 12 that with a server interface 14 is technically connected. The control module 12 Includes a low voltage electrical power supply to deliver regulated electrical power there. It will be appreciated that there are a variety of human-machine interface devices by which the vehicle operator controls the operation of the vehicle 100 commanding, for example, an ignition switch to allow an operator, the engine 40 To crank and start, an accelerator pedal, a brake pedal and a transmission range selector lever (PRNDL) included. Although the control module 12 and the operator interface 14 are shown as individual discrete elements, this representation is only to facilitate the description. It should be noted that the functions are described as being from the control module 12 be executed, may be combined in one or more devices, for. In software, hardware and / or an application specific integrated circuit (ASIC) and support circuitry separate and separate from the control module 12 are, can be implemented. It should be noted that an information transfer to and from the control module 12 using one or more communication links, e.g. B. the communication bus 18 , which may include a direct connection, a local network bus and / or a serial peripheral interface bus.

The control module 12 is preferably signaling and functional with individual elements of the hybrid powertrain system 20 over the communication bus 18 connected. The control module 12 is with the detection devices of the high voltage battery 25 , the rectifier / inverter module 30 , the first and second torque machines 35A and 35B , the power machine 40 and the hybrid transmission 50 signal-technically connected in order to monitor their mode of operation and to determine their parameter states.

Monitored parameter states of the engine 40 Preferably, the engine speed (Ni), the engine torque (Ti), or the engine load and the temperature. Monitored parameter states of the hybrid transmission 50 Preferably, the speed and hydraulic pressure are at a plurality of locations from which parameter conditions may be determined, including applying specific torque-transmitting clutches. Monitored parameter states of the torque machines 35 preferably include speeds N _A and N _B for the respective first and second torque machines 35A and 35B , Monitored parameter states of the torque machines preferably include power flows, e.g. B. an electric current flow from which a parameter state for engine torques T _A and T _B can be determined. Monitored parameter states of the high-voltage battery 25 include the battery power and the battery temperature.

The control module 12 is with the actuators of the rectifier / inverter module 30 including the first and second rectifier / inverter 32A and 32B , the power machine 40 and the hybrid transmission 50 functionally connected to control their operation in accordance with executed control schemes, which are in the form of algorithms and calibrations and stored. It should be noted that both the first and the second rectifier / inverter 32A and 32B transform electrical power in a manner suitable to torque in the first and / or second torque machine 35A and 35B and transform mechanical power in a manner suitable for electrical power with the first and / or second torque machines 35A and 35B dependent on. of torque inputs and operating conditions.

The control module 12 implements control schemes to a mode of operation of the engine 40 in coordination with the rectifier / inverter module 30 to control the overall operation of the hybrid powertrain system 20 to control the transmission of mechanical power to the driveline 60 and manage the electrical power flow to the high voltage battery 25 manage. Such control schemes include that of the operation of the engine 40 with acceptable battery power limits with the high voltage battery 25 are balanced, with an output torque to the final drive 60 is reached, which responds to an operator torque request. This includes the operation of the engine 40 is controlled to achieve a preferred engine speed associated with a peak efficiency or otherwise preferred efficiency.

Control module, module, controller, control unit, processor and similar terms designate any suitable or various combinations of one or more application specific integrated circuits (ASIC), electronic circuits, central processing units (preferably microprocessors) and associated random access memory and mass memory (read-only memory, programmable read-only memory, Random access memory, hard disk drive, etc.) executing one or more software or firmware programs, combinatorial logic circuits, input / output circuits and devices, appropriate signal conditioning and buffer circuits, and other suitable components that provide the described functionality. The control module 12 has a set of control algorithms containing resident software program instructions and calibrations stored in memory to provide the desired functions. The algorithms are preferably executed during preset loop cycles. The algorithms are executed by, for example, a central processing unit and may be operated to monitor inputs from detectors and other network control modules and to perform control and diagnostic routines for controlling the operation of actuators. Loop cycles may be performed at regular intervals, for example, every 3.125, 6.25, 12.5, 25, and 100 milliseconds during ongoing engine and vehicle operation. Alternatively, algorithms may be executed in response to the occurrence of an event.

2 schematically shows details of an electrical circuit that the high voltage battery 25 , the high voltage bus 29 including the positive side 29A and the negative side 29B , the rectifier / inverter module 30 and the first and second torque machines 35A and 35B contains. A DC coupling 31 , the positive and negative DC link busbars 31A respectively. 31B contains is with both the first and the second rectifier / inverter 32A and 32B coupled. A high voltage filter capacitor 33 is between the positive and the negative DC coupling 31A respectively. 31B electrically connected. A controllable discharge switch 34 , preferably in series with a resistive element, is across the DC coupling, ie between the positive and negative DC busbars 31A and 31B electrically coupled. A switch device 36 is between the positive DC link busbar 31A and the positive side 29A of the high voltage bus 29 placed. The negative DC link busbar 31B is with the negative side 29B the high voltage bus directly coupled. Alternatively, the switch device 36 between the negative DC busbar 31B and the negative side 29A of the high voltage bus 29 be placed and the positive DC busbar 31A can with the positive side 29A be coupled directly to the high voltage bus. The switch device 36 and / or the discharge switch 34 are controllable to the high voltage bus 29 and the DC coupling 31 to selectively couple and decouple electrically as described in further detail below. The switch device 36 and the discharge switch 34 are with the control module 12 electrically connected and are controlled by this. In one embodiment, the switch means includes 36 a pair of back-to-back power transistors, e.g. IGBT / FWD or MOSFET / FWD devices connected in parallel to allow electric current to flow in both directions between the high voltage battery 25 and the first and second rectifier / inverter 32A and 32B to control individually. Alternatively, the switch device contains 36 a single power transistor, e.g. B. an IGBT or MOSFET device which is connected in parallel with a forward biased diode device. Alternatively, the switch device contains 36 a mechanical switch device with high speed and high voltage.

The voltage potential across the positive and negative DC busbars 31A and 31B over the high voltage filter capacitor 33 Can be used to the second torque machine 35B using the second rectifier / inverter 32B to propel a drive torque to the driveline 60 to deliver.

The engine 40 Can be used to apply mechanical power to the first torque machine 35A transferred to. The first torque machine 35A in conjunction with the first rectifier / inverter 32A generates electrical power using mechanical power. The generated electrical power is applied to the positive and negative DC busbars 31A and 31B transferred and from there either the second rectifier / inverter 32A for operating the second torque machine 35B or the high voltage bus 29 to charge the high voltage battery 25 using energy and torque balance equations, or both.

The powertrain system control scheme controls and manages electrical power in one of several modes of operation, depending on the size of an operator torque request and a powertrain system capacity 20 to achieve a torque output responsive thereto.

In a first operating mode, the switch device is located 36 in a closed state, eliminating the high voltage bus 29 to the DC coupling 31 is clamped and electrical power between the high voltage battery 25 and the first and second rectifier / inverter 32A and 32B flows. In the first mode of operation is the DC coupling voltage, ie the voltage potential between the positive and negative DG coupling busbar 31A and 31B over the high voltage filter capacitor 33 equal to the voltage of the high voltage battery 25 , The engine torque output by the second torque machine 35B is therefore limited to what is achievable with the DC coupling voltage equivalent to the voltage of the high voltage bus 29 is (ie the voltage of the high voltage battery 25 ). In the first operating mode, there is an electrical energy balance between the high voltage battery 25 , the first torque machine 35A and the second torque machine 35B ,

In a second operating mode, the switch device is located 36 in an open state, eliminating the high voltage bus 29 from the DC coupling 31 is electrically decoupled and between the high voltage battery 25 and the first and second rectifier / inverter 32A and 32B no electrical power flows. In the second mode of operation is the DC coupling voltage, ie the voltage potential between the positive and negative DC busbars 31A and 31B not on the voltage of the high voltage battery 25 limited. Instead, the voltage potential between the positive and negative DC link busbars 31A and 31B over the high voltage filter capacitor 33 by the voltage from the first rectifier / inverter 32A based on input from the first torque machine 35A driven by the engine 40 is driven. Consequently, the voltage coming from the DC coupling 31 to the second rectifier / inverter 32B is delivered, greater than the voltage of the high voltage battery 25 be. Therefore, an equivalent engine torque output may be provided by the second torque machine 35B be achieved at lower motor currents, or the engine torque output by the second torque machine 35B may be larger at equivalent motor currents. In the second mode of operation, there is an energy balance between the first torque machine 35A and the second torque machine 35B ,

In a third mode of operation, the switch means 36 cyclically switched between the open state and the closed state, z. B. using a pulse width modulated signal (PWM signal) with a controllable duty cycle to an electrical power flow between the high voltage battery 25 and the first and second rectifier / inverter 32A and 32B to interrupt periodically. In the third mode of operation is the DC coupling voltage, ie the voltage potential between the positive and negative DC busbars 31A and 31B also not on the voltage of the high voltage battery 25 limited. Instead, the voltage potential between the positive and negative DC link busbars 31A and 31B over the high voltage filter capacitor 33 by the voltage from the first rectifier / inverter 32A based on input from the first torque machine 35A that from the engine 40 is driven, and the duty ratio of the PWM signal to the switch means 36 driven. Thus, the voltage coming from the DC coupling 31 to the second rectifier / inverter 32B is delivered, greater than the voltage of the high voltage battery 25 be. An equivalent engine torque output by the second torque machine 35B can therefore be achieved at lower engine currents, or the engine torque output by the second torque machine 35B may be larger at equivalent motor currents. The engine torque output by the second torque machine 35B may increase with an increase in the DC coupling voltage and may be limited to an upper voltage limit, e.g. B. 500 VDC be limited. In the third mode of operation, the energy balance between the first torque machine 35A and the second torque machine 35B attenuated by a periodic energy balance, the high voltage battery 25 includes.

3 schematically shows a control scheme for controlling the operation of a hybrid powertrain, z. B. with reference to 1 and 2 described hybrid powertrain 20 in response to the operator torque request.

During continuous operation of the powertrain system, an operator torque request (TO_REQ) is made using the operator interface 14 supervised ( 305 ).

In response to the operator torque request, a motor torque command is provided, preferably in the form of a motor torque command for the second torque machine 35B assumes the final drive 60 is transmitted (T _{B_CMD} = f (TO_REQ)) ( 310 ).

A preferred DC coupling _voltage (V _{DC_LINK_PRF} ) is determined ( 315 ), for example by calculations or reference, and this corresponds to the engine torque command for the second torque machine 35B that is attached to the driveline 60 is transmitted (T _{B_CMD} ). For example, a preferred DC coupling voltage may be determined so that the electrical machine current needed to achieve the motor torque command is minimized and thus ohmic heating is minimized. Alternatively or additionally, in determining the preferred DC coupling voltage, torque generation considerations may be applied to the second torque machine 35B be dominant. In addition to torque considerations for the second torque machine 35B For example, the preferred DC coupling _voltage (V _{DC_LINK_PRF} ) may also be due to an engine torque _command for the first torque _machine due to electrical energy _{balance considerations} 35A (T _{A_CMD} ) and it can be determined taking into account such considerations.

The DC _{link voltage} (V _{DC_LINK_MON} ) is continuously monitored and corresponds to the magnitude of the voltage from the high voltage _battery 25 on the high voltage bus 29 (V _BAT ) when the high voltage bus 29 clamped to the DC coupling (ie the switch means 36 closed is). The DC coupling voltage (V _{DC_LINK_MON} ) may _depend on the voltage of the high voltage _battery 25 on the high voltage bus 29 (V _BAT ) deviate when the high voltage bus 29 is not clamped to the DC coupling (ie when the switch means 36 open or controlled using a PWM signal with a controllable duty cycle to provide electrical power between the high voltage battery 25 flows, periodically interrupting).

From the above-mentioned first, second, and third operation modes, one based on the preferred DC _{link voltage} (V _{DC_LINK_PRF} ), the monitored DC _link voltage (V _{DC_LINK_MON} ), and the magnitude of the voltage from the high voltage _battery 25 on the high voltage bus 29 (V _BAT ) selected ( 320 ). The operation of the powertrain system 20 is in the selected first, second or third operating mode using the switch means 36 controlled to control the DC _{link voltage} (V _{DC_LINK} ) to an electrical power _flow between the high voltage battery 25 and the first and second rectifier / inverter 32A and 32B to control. Alternatively, the operation of the powertrain system 20 in the selected first, second or third operating mode using the discharge switch 34 controlled to the DC link voltage (V _{DC_LINK} ) to control the electrical power flow between the high voltage _battery 25 and the first and second rectifier / inverter 32A and 32B to control.

The hybrid powertrain system 20 selects the first mode of operation (MODE 1) when the preferred DC coupling _voltage (V _{DC_LINK_PRF} ) and the monitored DC coupling voltage (V _{DC_LINK_MON} ) is equal to or less than the magnitude of the voltage from the high voltage _battery 25 on the high voltage bus 29 (V _BAT ) are. The switch device 36 is controlled in the closed state and electrical power flows between the high voltage battery 25 and the first and second rectifier / inverter 32A and 32B via the positive and negative DC link busbar 31A and 31B , In the first mode of operation, the preferred DC coupling voltage (V _{DC_LINK_PRF} ) _becomes equal to the voltage from the high voltage _battery 25 on the high voltage bus 29 (V _BAT ) is set.

The hybrid powertrain system 20 operates in the second operating mode (MODE 2) when the preferred DC coupling voltage (V _{DC_LINK_PRF} ) is greater than the voltage from the high voltage _battery 25 on the high voltage bus 29 (V _BAT ) and the monitored DC coupling voltage (V _{DC_LINK_MON} ) is less than an upper voltage _limit (V _THD ). The switch device 36 is controlled in the open state to electrical power between the high voltage battery 25 and the first and second rectifier / inverter 32A and 32B flows, completely interrupting. The monitored voltage potential between the positive and negative DC busbars 314 and 31B over the high voltage filter capacitor 33 ie, the monitored DC coupling voltage (V _{DC_LINK_MON} ) is the voltage of the first rectifier / inverter 32A based on input from the first torque machine 35A driven by the engine 40 is driven. Operation in the second mode of operation continues as long as the preferred DC coupling voltage (V _{DC_LINK_PRF} ) is greater than the voltage from the high voltage _battery 25 on the high voltage bus 29 (V _BAT ) and the monitored DC coupling voltage (VDC_LINK_MON) is less than the upper voltage limit (V _THD ), z. B. 500 VDC is. The upper voltage limit (V _THD ) is associated with design limitations and operating capabilities of the various powertrain components, including but not limited to the positive and negative DC busbars 31A and 31B , the first and second rectifier / inverter 32A and 32B and the first and second torque machines 35A and 35B , In the second operating mode, the preferred DC coupling _voltage (V _{DC_LINK_PRF} ) is the value that was previously determined, for example, by calculations or reference ( 315 ).

The hybrid powertrain system 20 operates in the third operating mode (MODE 3) when the monitored DC _link voltage (V _{DC_LINK_MON} ) is equal to or greater than the upper voltage _limit (V _THD ). Operation in the third mode of operation includes the switch device 36 is controlled using a PWM signal with a controllable duty cycle to provide electrical power flow between the high voltage battery 25 and the first and second rectifier / inverter 32A and 32B periodically interrupt the monitored DC _{link voltage} (V _{DC_LINK_MON} ) across the filter capacitor 33 to reduce. Alternatively, the operation in the third operation mode includes that of the discharge switch 34 is controlled with the controllable duty cycle using the PWM signal to provide electrical power across the filter capacitor 33 and the first and second rectifier / inverter 32A and 32B periodically to reduce the monitored DC _{link voltage} (V _{DC_LINK_MON} ). Alternatively, both the switch device 36 as well as the discharge switch 34 controlled using the PWM signal to periodically discharge electrical power ( 330 ). The monitored voltage potential between the positive and negative DC busbars 31A and 31B over the high voltage filter capacitor 33 ; that is, the monitored DC dome voltage (V _{DC_LINK_MON} ) is from the voltage of the first rectifier / inverter 32A based on input from the first torque machine 35A driven, which of the engine 40 is driven. Operation in the third mode of operation continues as long as the monitored DC _link voltage (V _{DC_LINK_MON} ) is greater than the upper voltage _limit (V _THD ).

The hybrid powertrain system 20 operates in the first, second or third operating mode to the operation of the first and second torque machine 35A and 35B in response to the operator torque request ( 325 ). A preferred control _{scheme includes} determining the preferred DC _{link voltage} (V _{DC_LINK_MON} ) and the motor torque _command for the second torque _machine 35B as described above to the final drive 60 (T _{B CMD} ) is transmitted. Monitored states of the hybrid powertrain system 20 include a current speed (N _A ) of the first torque machine 35A and the monitored DC _{link voltage} (V _{DC_LINK_MON} ). A proportional (P) and integral (I) control logic is executed to provide a motor torque command for the first torque machine 35A (T _{A_CMD} ) in response to the current speed (N _A ) of the first torque _machine 35A and determine a difference between the monitored DC coupling _voltage (V _{DC_LINK_MON} ) and the preferred DC coupling _voltage (V _{DC_LINK_MON} ). Torque compensation (torque compensation) occurs between the engine torque command for the first torque machine 35A (T _{A_CMD} ) and the engine torque _command for the second torque _machine 35B (T _{B_CMD} ) executed to final motor torque _commands for the first and second torque _machine 35A and 35B to determine, ie T _{A FINAL} and T _{B_FINAL} .

4 Graphically illustrates the simulated operation of the hybrid powertrain system 20 using the with respect to 3 described control schemes, which controls the switching device 36 to maintain the monitored DC _link voltage (V _{DC_LINK_MON} ) at or below the upper voltage _limit (V _THD ), and maintaining a balanced torque output by the first and second torque machines 35A respectively. 35B includes.

The disclosure has described certain preferred embodiments and modifications thereto. While reading and understanding the description, others may encounter further modifications and changes. It is therefore intended that the disclosure not be limited to the particular embodiments disclosed which are believed to be the best mode for carrying out this disclosure, but that the disclosure will include all embodiments falling within the scope of the appended claims.

Claims (10)

A method of operating a hybrid powertrain system including a high voltage electrical circuit including a high voltage battery and a DC coupling coupled to first and second rectifiers / inverters electrically connected to first and second torque machines, the method comprising: receiving an engine torque command for the second torque machine; determining a preferred DC coupling voltage for achieving the commanded motor torque by the second torque machine, and electrical power flow between the high voltage battery and the DC coupling is selectively interrupted to achieve the preferred DC coupling voltage. The method of claim 1, wherein selectively interrupting the electrical power flow between the high voltage battery and the DC coupling to achieve the preferred DC coupling voltage comprises permanently interrupting the electrical power flow between the high voltage battery and the DC coupling when the DC power supply preferred DC coupling voltage is greater than an output voltage of the high voltage battery. The method of claim 1, wherein selectively interrupting the electrical power flow between the high voltage battery and the DC coupling to achieve the preferred DC coupling voltage comprises periodically interrupting the electrical power flow between the high voltage battery and the DC coupling, if any monitored DC coupling voltage is greater than a threshold voltage. The method of claim 3, wherein periodically interrupting the electrical power flow between the high voltage battery and the DC coupling comprises controlling a switch coupled between the high voltage battery and the DC coupling to control the electrical power flow between the high voltage battery and the high voltage battery Selectively interrupting DC coupling to achieve the preferred DC coupling voltage. The method of claim 4, wherein controlling the switch to selectively interrupt the electrical power flow between the high voltage battery and the DC coupling comprises performing pulse width modulated control of the switch coupled between the high voltage battery and the DC coupling. to selectively interrupt the electrical power flow between the high voltage battery and the DC coupling to achieve the preferred DC coupling voltage. The method of claim 3, wherein periodically interrupting the electrical power flow between the high voltage battery and the DC coupling comprises controlling a switch coupled via the DC coupling to selectively interrupt the electrical power flow between the high voltage battery and the DC coupling to achieve the preferred DC coupling voltage. The method of claim 6, wherein controlling the switch to selectively interrupt the electrical power flow between the high voltage battery and the DC coupling comprises performing pulse width modulated control of the switch coupled via the DC coupling to the switch selectively interrupting electrical power flow between the high voltage battery and the DC coupling to achieve the preferred DC coupling voltage. The method of claim 1, wherein selectively interrupting the electrical power flow between the high voltage battery and the DC coupling to achieve the preferred DC coupling voltage comprises maintaining the electrical power flow between the high voltage battery and the DC coupling permanently when the DC power supply preferred DC coupling voltage is smaller than an output voltage of the high voltage battery. A method of operating a hybrid powertrain system including an engine and first and second torque machines coupled to a transmission device for transmitting torque to a driveline and a high voltage electrical circuit including a high voltage battery, a DC coupling coupled to first and second Rectifiers / inverters are electrically connected to the first and second torque machines and includes a switch which is configured to interrupt an electric power flow between the high voltage battery and the first and second rectifier / inverter when it is in an open state controlled, the method comprising: commanding an engine torque output from the second torque machine in response to an operator torque request; determining a preferred DC link voltage to achieve the commanded motor torque output by the second torque machine; and the switch is controlled to selectively interrupt the electrical power flow between the high voltage battery and the first and second rectifier / inverter to achieve the preferred DC coupling voltage. Hybrid powertrain system comprising: an engine and first and second torque machines coupled to a transmission for transmitting torque to a driveline; a high voltage electrical circuit comprising a high voltage battery, a rectifier / inverter module and a switch, the high voltage battery being electrically coupled to the rectifier / inverter module via a DC coupling, the rectifier / inverter module having the first and second torque machines is functionally electrically connected and the switch is configured to interrupt an electrical power flow between the high voltage battery and the rectifier / inverter module when it is controlled in an open state; and a controller that monitors a voltage of the high voltage battery and a voltage across the DC coupling, determines a preferred voltage across the DC coupling, and controls the switch to responsive to electrical power flow between the high voltage battery and the rectifier / inverter module break the voltage of the high voltage battery, the voltage across the DC coupling, and the preferred voltage across the DC coupling.

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